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This article presents a mathematical continuum model to analyze the free vibration response of cross-ply carbon-nanotube-reinforced composite laminated nanoplates and nanoshells, including microstructure and length scale effects. Different shell geometries, such as plate (infinite radii), spherical, cylindrical, hyperbolic-paraboloid and elliptical-paraboloid are considered in the analysis. By employing Hamilton’s variational principle, the equations of motion are derived based on hyperbolic sine function shear deformation theory. Then, the derived equations are solved analytically using the Galerkin approach. Two types of material distribution are proposed. Higher-order nonlocal strain gradient theory is employed to capture influences of shear deformation, length scale parameter (nonlocal) and material/microstructurescale parameter (gradient). Temperature-dependent material properties are considered. The validation of the proposed mathematical model is presented. Detailed parametric analyses are carried out to highlight the effects of the carbon nanotubes (CNT) distribution pattern, the thickness stretching, the geometry of the plate/shell, the boundary conditions, the total number of layers, the length scale and the material scale parameters, on the vibrational frequencies of CNTRC laminated nanoplates and nanoshells.

The present study demonstrates the free vibration behavior of composite laminated shells reinforced by both randomly oriented single-walled carbon nanotubes (SWCNTs) and functionally graded fibers. The shell structures with different principal radii of curvature are considered, such as cylindrical, spherical, elliptical–paraboloid shell, hyperbolic–paraboloid shell, and plate. The volume fraction of the fibers has a linear variation along the shell thickness from layer to layer, while the volume fraction of CNTs is constant in all shell layers and uniformly distributed. The fiber-reinforced elements are distributed with three functions which are V-distribution, O-distribution, and X-distribution in addition to the uniform distribution. A numerical analysis was carried out systematically to validate the proposed solution. A new analytical solution is presented based on the Galerkin approach for shells and is exploited to illustrate the influence of some factors on the free vibration behavior of CNTs/fibe-reinforced composite (CNTs/F-RC) laminated shells, including the distributions and volume fractions, various boundary conditions, and geometrical properties of the reinforcement materials. The proposed solution is shown to be an effective theoretical tool to analyze the free vibration response of shells.

Brain tumors reduce life expectancy due to the lack of a cure. Moreover, their diagnosis involves complex and costly procedures such as magnetic resonance imaging (MRI) and lengthy, careful examination to determine their severity. However, the timely diagnosis of brain tumors in their early stages may save a patient’s life. Therefore, this work utilizes MRI with a machine learning approach to diagnose brain tumor severity (glioma, meningioma, no tumor, and pituitary) in a timely manner. MRI Gaussian and nonlinear scale features are extracted due to their robustness over rotation, scaling, and noise issues, which are common in image processing features such as texture, local binary patterns, histograms of oriented gradient, etc. For the features, each MRI is broken down into multiple small 8 × 8-pixel MR images to capture small details. To counter memory issues, the strongest features based on variance are selected and segmented into 400 Gaussian and 400 nonlinear scale features, and these features are hybridized against each MRI. Finally, classical machine learning classifiers are utilized to check the performance of the proposed hybrid feature vector. An available online brain MRI image dataset is utilized to validate the proposed approach. The results show that the support vector machine-trained model has the highest classification accuracy of 95.33%, with a low computational time. The results are also compared with the recent literature, which shows that the proposed model can be helpful for clinicians/doctors for the early diagnosis of brain tumors.

Biomedical alloys have gained significant attention due to their high strength, good corrosion resistance, and biocompatibility. These alloys are widely used in orthopedic, dental, and cardiovascular devices. Co-Cr-Mo-based alloys have been extensively used among these alloys due to their excellent mechanical properties and biocompatibility. Si has been added to the alloy matrix to improve the wear resistance and mechanical properties of Co-Cr-Mo-based biomedical alloys. Si has been reported to enhance metallic biomaterials’ mechanical properties and wear resistance. The effect of Si addition on the microstructure, mechanical properties, and wear rate of Co-Cr-Mo-based biomedical alloys is investigated. Si with different percentages (0.5-2.5wt.%) is added to the Co-Cr-Mo-based alloy. The results revealed a significant improvement in hardness and wear resistance. The inclusion of Si resulted in the formation of chromium silicide (Cr 3 Si) phases, which have a much higher hardness. It contributed significantly to enhancing the hardness and, thus, the wear resistance of these alloys. The results revealed that the wear resistance is enhanced by 73.5% and 40.75% for (2.5wt.%) (2.0wt.%) Si content, respectively. The hardness is improved by 30% when the Si content reaches 2.0% and then reduced as the Si (wt%) increases.

The dynamic and flexural behavior of pultruded glass fiber reinforced polymer GFRP rebars were investigated after exposure to elevated temperatures ranging from room temperature to 290 °C. The rebars were cut and grouped into two sets. The first set contained the uncoated specimens, and the second set enclosed the specimens that had been coated with a gun-sprayed thin layer of silicon matrix mixed with ceramic nanoparticles as an insulation medium. All specimens’ dynamic and flexural performances were experimentally performed after heating them inside the oven for 6 h and later cooled down outside the oven at room temperature for 24 h. The dynamic results of the coated specimens showed slight changes in the damping ratio due to the effectiveness of the coating layer. In contrast, the uncoated specimens showed a gradual increase in the damping ratio ranging from 12.5% to 43.1%. Similarly, the tested flexural strength of the coated specimens provided slight changes within the elevated temperatures, while the uncoated specimens showed a gradual decrease ranging from 3.9% to 6.4%.

The occurrence of a hybrid effect for sandwich panels made from inter-laminar hybrid composite face sheets and a rigid foam core with respect to buckling performance was the subject of investigation in this study. As a first step, this study performed experiments and validated the results using analytical predictions and numerical simulations. Second, a comprehensive comparison of the experimental, analytical and numerical results was used to confirm the occurrence of a hybrid effect, which was the study's major objective. Experimentally, all the sandwich panels were fabricated using the Vacuum Assisted Resin Transfer Molding (VARTM) process by double infusing the resin through the sandwich panel face sheets simultaneously. A set of compressive tests were performed to optimize the dimensions of the buckling test specimens that delivered the most clear and recordable out-of-plane deflection using non-contact laser sensors. Additionally, flexural 3-point bending tests were performed to investigate the existence of a hybrid effect within the six hybrid specimens made from 2:2 hybrid (glass:carbon) fiber face sheets and to study their ability to delay the yield and ultimate loading points. The hybrid specimen results were compared to two baseline specimens made from sandwich panels with all-glass or all-carbon face sheets. The chances of face sheet failure were higher when the carbon fiber layers were placed at or near the outer side of the face sheet lamina during the bending tests. Moreover, the best flexural performance was delivered by the specimens with balanced face sheets. Finally, the buckling behavior of the six different sandwich panels were investigated compared to the two baseline sandwich panels. The out-of-plane deflection of each specimen was measured by back-to-back reflex non-contact laser sensors to capture the negative and positive deflections on both sides of the specimen. The experimental buckling results showed a positive hybrid effect in the hybrid specimen with an alternating order of glass and carbon lay-up in delaying the critical buckling load by 11.4% to 18.3%. A microscopic examination was performed to investigate the failure modes and their mechanisms caused by both the flexural 3-point bending tests and the buckling tests.

Light-chain deposition disease (LCDD) reoccurs almost invariably after renal transplantation, leading to early graft loss. We report a case of LCDD with monoclonal gammopathy of renal significance diagnosed in the post-transplant period in a 28-year-old male and we discuss the diagnostic and therapeutic challenges in the clinical course

Field experiment was carried out at the experimental research station of Nubaria, representing the newly reclaimed sandy loam soils of Egypt. The study was done to evaluate the nutrient status of barley varieties (Egyptian, Tunisian, Algerian and Morocco) grown under normal (75% water holding capacity=WHC) and stress condition (40% WHC). Results indicated that the Egyptian variety El-Arish scored the highest values of N% under normal and drought stress condition and Giza 127 for P and Giza 123 for K in same sequence. The lowest values of N, P and Ca content observed with Giza 2000 variety. As for the Tunisian varieties, the lowest reduction percentage was attained at Raihane (9.38%, 3.54% and 3.62%) for N, K and Ca, respectively. Algerian barley varieties, N in Naïlia/Techedrett, P in Temacine/Ksar Megrine, K in Ras El-Mouche/Temacine, Ca in Saida/Ksar Megrine, got the highest and lowest values under normal and stress conditions, respectively. Morocco varieties, lowest values of N, P, K and Ca were recorded for Massine, Taffa and Amalou under water stress condition. The highest and lowest value of Fe, Zn and Mn were recorded for barley varieties Giza 2000, Giza 131 and Giza 127, respectively. Results concluded that the Egyptian varieties (Giza 127, Giza131, Giza 2000), Tunisian varieties (Kebili-3 and Tozeur-2), Algerian varieties (Techedrett, Naïlia) and Morocco varieties (Laanaceur, Amira) registered the lowest reduction percentage in nutrient content indicating their tolerance to sustain its productivity under water stress condition.

Cet article scientifique a pour objectif de définir : les processus de décision, leurs différents mécanismes et modes de préparation et leurs composants, ainsi que leurs étapes, d'une part, la performance dans les entreprises économiques, d'autre part, et enfin, une étude quantitative sur l'effet de la stabilité dans la prise de décision sur la performance commerciale en étudiant le cas d'une grande entreprise publique économique. Nous avons conclu que la décision relative à la participation aux soumissions influence relativement la performance commerciale alors que cette dernière n'est pas influencée par la décision de passation de contrats de gré à gré.

Cet article aborde le thème de l'exclusion dans «Cette fille- là» chez Maïssa Bey. Nous traiterons les différentes interprétations de ce concept pour aboutir à une définition plus précise. Nous tenterons d'y dégager les manifestations de l'exclusion à travers les figures d'exclues qui figurent dans le roman, objet d'étude, telles que: les vieilles, les bâtardes et le deuxième sexe: chaque protagoniste est délabré sur le plan physique ainsi que sur le plan moral et son identité est clairement posé comme étant problématique. Notons aussi que la femme est la plus touchée par l'exclusion en raison de son sexe. De plus, l'étude des voix des personnages s'avère importante pour analyser l'oralité et la polyphonie. Quant au cadre spatio-temporel, nous nous pencherons sur le mouvement et le déplacement des exclues. Ces dernières oscillent entre un espace de fuite et un autre de séquestration. Ces deux voies ne sont que les revers de la même médaille: l'exclusion. Et enfin en ce qui concerne la temporalité, elle marque l'acheminement du personnage vers l'errance, la dérive, la décomposition et la mort puisqu'il est assailli par l'assombrissement d'une nuit permanente qui reflète son existence.